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排序方式: 共有9893条查询结果,搜索用时 218 毫秒
931.
Yuh-Shyan Hwang Pei-Tzu Hung Wei Chen Shen-Iuan Liu 《Analog Integrated Circuits and Signal Processing》2002,32(2):123-134
A transformation called current-mode linear transformation (CMLT) and its filter applications using multiple output second-generation current conveyors (MOCCIIs) are presented. The systematic method is developed to realize CMLT MOCCII-based filters efficiently. Based on the proposed design tables, we can synthesize high-order current-mode all-pole and elliptic filters with MOCCIIs, grounded resistors and capacitors. Moreover, the high-frequency elliptic filter can also be efficiently realized by adding capacitors to the relative all-pole filter, although floating capacitors are needed. Third-order Chebychev and elliptic lowpass filters are described in this paper. Experimental results that confirm the theoretical analysis are obtained. Furthermore, the proposed circuits can be extended to higher-order filters. 相似文献
932.
Ü. Özgür X. Gu S. Chevtchenko J. Spradlin S. -J. Cho H. Morkoç F. H. Pollak H. O. Everitt B. Nemeth J. E. Nause 《Journal of Electronic Materials》2006,35(4):550-555
Thermal conductivities (κ) of melt-grown bulk ZnO samples thermally treated under different conditions were measured using
scanning thermal microscopy. Samples annealed in air at 1050°C for 3 h and treated with N-plasma at 750°C for 1 min. exhibited
κ=1.35±0.08 W/cm-K and κ=1.47±0.08 W/cm-K, respectively. These are the highest values reported for ZnO. Atomic force microscopy
(AFM) and conductive-AFM measurements revealed that surface carrier concentration as well as surface morphology affected the
thermal conductivity. 相似文献
933.
S.I. Jung J.J. Yoon H.J. Park Y.M. Park M.H. Jeon J.Y. Leem C.M. Lee E.T. Cho J.I. Lee J.S. Kim J.S. Son J.S. Kim D.Y. Lee I.K. Han 《Physica E: Low-dimensional Systems and Nanostructures》2005,26(1-4):100
We investigate the effects of a thin AlAs layer with different position and thickness on the optical properties of InAs quantum dots (QDs) by using transmission electron microscopy and photoluminescence (PL). The energy level shift of InAs QD samples is observed by introducing the thin AlAs layer without any significant loss of the QD qualities. The emission peak from InAs QDs directly grown on the 4 monolayer (ML) AlAs layer is blueshifted from that of reference sample by 219 meV with a little increase in FWHM from 42–47 meV for ground state. In contrast, InAs QDs grown under the 4 ML AlAs layer have PL peak a little redshifted to lower energy by 17 meV. This result is related to the interdiffusion of Al atom at the InAs QDs caused by the annealing effect during growing of InAs QDs on AlAs layer. 相似文献
934.
Ram Sharma Tiwaree Kyeoung-scik Cho Mitsgyo Hirai Makoto Shoda 《Applied biochemistry and biotechnology》1992,32(1-3):135-148
Biological deodorization of dimethyl sulfide (DMS) was studied using nine unwoven fabrics as the carriers of microorganisms in a laboratory-scale deodorizing system. The activated carbon fabric FN-200CF-15 was the best packing material compared with other packing materials used, on the basis of removal rate. The maximum removal rate (Vm), evaluated by using Michaelis-Menten equation, was 2.28 g-Skg-dry fab.-1 day-1 in this fabric biofilter. The critical load of DMS in this fabric biofilter was dependent on space velocity (SV), determined as 0.78 and 0.66 g-Skg-dry fab.-1 at SV 100 and 150 h-1, respectively. Strain IM1 isolated from the carbon fabric FN-200CF-15 biofilter in modified Waksman (MW) medium successfully degraded DMS as well as hydrogen sulfide (H2S), methanethiol (MT), and dimethyl disulfide (DMDS) in batch test. The DMS removal rates (g-S cell-1h-1) by this strain measured in batch culture and calculated in FN-200CF-15 biofilter by the cell numbers appeared in MW medium were found almost equal, indicating that strain IM1 may be the dominant microorganism in this biofilter. 相似文献
935.
Let X be an arbitrary Banach space, K be a nonempty closed convex subset of X, and T : K → K be a Lipschitzian and hemicontractive mapping with the property lim inft→∞((t)/t) > 0. It is shown that the Ishikawa iteration procedures are weakly T-stable. As consequences, several related results deal with the weak stability of these procedures for the iteration proximation of solutions of nonlinear equations involving accretive operators. Our results improve and extend those corresponding results announced by Osilike. 相似文献
936.
By relaxing the unrealistic assumption of probabilistic independence on activity durations in a project, this paper develops a hierarchical linear Bayesian estimation model. Statistical dependence is established between activity duration and the amount of resource, as well as between the amount of resource and the risk factor. Upon observation or assessment of the amount of resource required for an activity in near completion, the posterior expectation and variance of the risk factor can be directly obtained in the Bayesian scheme. Then, the expected amount of resources required for and the expected duration of upcoming activities can be predicted. We simulate an application project in which the proposed model tracks the varying critical path activities on a real time basis, and updates the expected project duration throughout the entire project. In the analysis, the proposed model improves the prediction accuracy by 38.36% compared to the basic PERT approach. 相似文献
937.
Non-ideal behavior of a driving resonator loop in a vibratory capacitive microgyroscope 总被引:1,自引:0,他引:1
Many researches have been carried out on the dynamic characteristics of vibratory microgyroscope, but only a few have been carried out on the non-ideal behaviors observed in the driving loop of the vibratory microgyroscope. In this paper, characterization and evaluation of the non-ideal behavior of the vibratory microgyroscope, “peak-and-valley” magnitude phenomenon and phase lag distortion, are discussed. To characterize the non-ideal behavior of a microgyroscope driving loop, a new electro-mechanical simulation model based on the HSPICE of microgyroscope driving loop is proposed. The parasitic capacitive components of the driving loop are found to be the major sources of non-ideal behavior in microgyroscope and it is verified with the simulation results. The validity of the proposed simulation model and the parasitic effects on microgyroscope driving loop is evaluated with the actual fabricated gyroscope. 相似文献
938.
939.
Caleb Yu-Sheng Cho Ming-Jer Chen Jia-Han Lin Chiou-Feng Chen 《Electron Device Letters, IEEE》2002,23(7):422-424
Overestimation of capacitance coupling coefficients in flash memory cells is encountered in the subthreshold slope method. By means of a two-parameters subthreshold current model ID=I0 exp[q(VGB - nVSB)/nkT], a mathematical formulation of the subthreshold swing ratio in the subthreshold slope method is constructed to isolate the measurement errors caused by process variations from the errors traditionally caused by bulk capacitance coupling. To minimize the effect of process variations, a new method is developed based on the model. In this method, the control gate voltage shift due to weak body effect is measured in flash memory cells in subthreshold, while the corresponding slope factor n is adequately deduced from threshold voltage versus source-to-substrate bias measurement in dummy devices. The corrected capacitance coupling coefficients show large improvements compared to the design values, and the updated errors are found to be close to that caused solely by bulk capacitance coupling. The method is also fast since only a small source-to-substrate bias of 0.1 V is needed for implementation of weak body effect, and thereby it can be used as an in-line monitor of capacitance coupling coefficients 相似文献
940.
We present a facile method for the self-directed growth of 1D molecular lines on the H-terminated Si(001) surface. Instead of a previously employed single dangling bond, we here employ a single H-free Si dimer as a reaction site, resulting in an enhanced stability of the radical intermediate for the O-phthalaldehyde (OP) molecule containing two carbonyl groups. This radical intermediate easily abstracts two H atoms from a neighboring Si dimer, thereby allowing the chain reaction for a 1D molecular line. Such a fabricated OP line will be stable at higher temperatures compared to previously reported alkene lines because of its enhanced stability. 相似文献